The present invention relates to a liquid crystal display device, and more particularly to a technique which is effectively applicable to a backlight which accommodates a light guide plate, an optical sheet group and the like or a technique which is effectively applicable to a flexible printed wiring board.
A liquid crystal display module of a TFT (thin film transistor) system having a miniaturized liquid crystal display panel with the number of sub pixels of approximately 240×320×3 in color display has been popularly used as a display part of a portable equipment such as a mobile phone.
In general, a liquid crystal display module includes a liquid crystal display panel and a backlight which radiates light to the liquid crystal display panel. With respect to the liquid crystal display module which is used as a display part of a portable equipment such as a mobile phone, the backlight is constituted of a resin frame mold (hereinafter referred to as mold), an optical sheet group and a light guide plate which are arranged in the inside of the mold, a reflection sheet which is arranged below the light guide plate, and a light source (for example, a white light emitting diode) which is arranged on a side surface of the light guide plate.
FIG. 13A to FIG. 13C are views for explaining the liquid crystal display module for a conventional mobile phone. FIG. 13A is a view as viewed from above (a liquid crystal display panel side, a front side, or a viewer's side), FIG. 13B is a view as viewed in a side view, and FIG. 13C is a view as viewed from below (a light guide plate side, a back-surface side, or a back side).
In the liquid crystal display module shown in FIG. 13A to FIG. 13C, a flexible printed wiring board (hereinafter, referred to as an FPC) 11 is folded and is wrapped around and fixed to the back surface side of the backlight for realizing the miniaturization and the reduction of thickness.
Further, on the FPC 11, electronic parts such as resistors and capacitors, and a white light emitting diode 15 which constitutes a light source are mounted. The white light emitting diode 15 is arranged in the vicinity of a folded portion of the FPC 11 and is arranged so as to face a light incident surface of a light guide plate not shown in the drawings in an opposed manner.
Here, when the FPC 11 is wrapped around the back surface from a terminal portion of the liquid crystal display panel with a minimum radius, the FPC 11 possesses a strong bending repulsive force (hereinafter, referred to as a spring-back force) and hence, the vicinity of the folded portion is fixed to a mold 1 using a pressure-sensitive adhesive double-coated tape 31.
Here, in FIG. 13A to FIG. 13C, numeral 4 indicates a reflection sheet which constitutes a portion of the backlight, numeral 7 indicates an upper polarizer, and numeral 12 indicates a semiconductor chip which constitutes a drive circuit.
Here, as prior art documents relevant to the present invention, following patent documents can be named.
[Patent Document 1] JP-A-2001-133756
[Patent Document 2] JP-A-2004-29651
[Patent Document 3] JP-A-2004-62048